1. Field of the Invention
The present invention relates to a method for adjusting rotating speed of a compact disc drive, and more particularly, to a method for adjusting the rotating speed of a compact disc drive such that vibrations of the rotating compact disc are prevented.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a diagrammatic view of a compact disc 10 with its weight unevenly distributed over its surface area. Manufacturing errors or unevenly distributed composition may cause a center of mass of the compact disc 10 to be deviated from its geographic center. If the mass of the compact disc 10 is m and the distance between its center of mass and its geographic center is r, a torque EQU .tau.=m*r
will be generated. When the compact disc 10 is rotated at an angular velocity w, a centrifugal force EQU F=m*r*w.sup.2
will be generated.
The centrifugal force F is directly proportional to the torque .tau. and the square of the angular velocity w of the compact disc 10. Thus, when rotating the compact disc 10 at a high speed, a strong centrifugal force will be generated even if the torque .tau. is small. Such a strong centrifugal force will cause the compact disc 10 to vibrate and which in turn, will cause a compact disc drive to vibrate with it. The vibrations will create bothering noise and prolong the time to read data from the compact disc 10.